Immersun solar diverter

Has anyone got any opinions on these.

They recon they work ok with batteries but real world experience is always better.

I had an immersun pre-battery, worked well then and works well in conjunction with the batteries. The house and batteries get first call before the immersun gets a look in. On good days both batteries and immersion are at 100% by the end of the day.

locked thanks

This one is a new model this year and apparently works much better. I have ordered a solar immersion unit - which is effectively the same company I think but they have said it doesn’t work well with batteries and recommended the immersun one would be better. Also claimed a faster payback but frankly I don’t believe the numbers.

Solar iBoost does the same thing AFAIK and is considerably cheaper. Mine works fine!

the current immersun is roughly double what I paid. They went out of business before being resurrected. I was told the folk that worked on the original immersun now work for myenergi. Per @wilfleek for value for money / bang for the buck something like the iBoost is the way to go ( in terms of real world experience I can only comment on my immersun)

locked Curious about how long it takes to recover the cost of one of these vs a simple relay that puts the immersion heater on at midday when generation is notionally at its peak and the battery most likely has sufficient charge to cover any shortfall. It was a good solution before domestic battery storage came along.

stevelewis I did this yesterday as an “emergency” get rid of some solar as the battery was nearly charged and I was exporting about 1kw. I used a Shelley switch and Homeassistant- which worked but it did seem to pull some in off the grid until the battery wound up to take over. And then the sun would disappear and the heater turn off. Still i got about 2.8Kwh into the water before the sun had dropped off again.

anglefire Way to go for under £20 :-)

@anglefire you can do a rough calculation by looking at how much excess you have in total (say per year), work out how much water you can heat with that for the size immersion element you have. Then work out how much it would cost to heat using conventional means (gas).

The benefit of diverters like iboost/immersun is they direct just the excess to the immersion so work even if there is only a small amount of excess. With the on off switch approach the immersion element will draw a constant load (typically 3kwh) which can be ok in summer months but for much is the year does not work so well when there is more cloud / variation in conditions.

Interested to see what the ROI looks like for for you particularly with the increase in in cost of energy

Can’t recommend the Solic. I’ve just finished mine off (by using it. How dare I?) in less than 12 months.
And I was a big flag bearer for it up to now.
(Although they are replacing it I suspect this will get a bit boring every year until the warranty expires in 9 years…)

An airing cupboard/hot water cylinder cupboard is always going to be a tough environment for domestic electronics. Lots of heat and little air movement. Still, they should last longer than 12 months!
Regarding payback times-this isn't always the primary driver. For me it means reducing the gas usage, which reduces the carbon footprint. Plus it keeps as much as possible of my self-generation inside the house which, to be honest, tickles me. I like having "free" hot water.

That is a correct assumption of electronics in an airing cupboard. Unfortunetly I had installed it in the cold garage so unless I should have given it a wooly hat or something it's not had a stressed life.
It didn't even go out in a fun way with a big bang or magic smoke or anything. Just "no output for you mwuhahahaha"

stevelewis you can have a longer heating window that still avoids grid import by installing a lower wattage immersion heater, say 2kW or 1.5kW. Thats well in the range of a smart switch to turn on an off and closer to what the inverter can produce. Simple logic of SOC / PV / Load to determine if to switch on

The lower power means the battery will cope even if the sun goes in. Just set for a trigger of say 30 mins. When that finishes resample the environment, restart another cycle if still plenty of spare energy

Yes it takes longer to heat water than than 3kW but its the total energy that matters and the levers for control are a lot easier. I am also measuring how much energy goes into the water. Once enough for a couple of showers in the morning I switch off the hot water and switch on the granny charger to the EV using exactly the same logic. Spread the energy based on the priorities I choose

Seye the immersun can control up to 3 loads of I read the data sheet correctly.

They even suggest an ev charger. Though it’s based on priority as one gets satisfied it moves on or on time.
But would be simple enough to “open the stat” on the first, hws, load when deemed enough hot water and move onto the ev. Also means at least for the hws the load is modulating so avoids export as well as discharging the battery to satisfy the hws load which will have some losses.

My old dual immersion heater has two settings, half tank short element at 2.2 kW and the full tank long element at 3.3 kW (roughly) and using a 16 amp smart switch works OK for now.

In the winter I'm resigned to not enough excess solar for water at all, let alone with variable power re: iBoost locked but I guess it would help a bit on those days the battery gets to 100%. There's something to be said for optimising the PV for avoided carbon emissions Zakalwe rather than £, either in terms of current grid CO2e or natural gas. I need to look into that a bit more :-).

But what I would love is a variable power immersion element with wi-fi/zigbee control that also told me the current temp. At a decent price. Seems a gap in the market? I could live without variable power I suppose.

jkazer
I don't know that much about these devices, but the Solar iBoost has the ability to connect to two immersion heaters. You can prioritise heating that way.

While waiting for any more details or pricing for the Givenergy power diverter I have set my Mixergy tank to heat (using the ASHP) at 2pm when the battery should be full, but there is still time for it to recharge should battery power be used during the water heating. Heating the whole tank seems to take about an hour, but I also heat during the cheap rate period so seldom start from less than 20% hot.
I like the idea of the power diverter just doings it thing, but actually I’d hope that a smart solar/battery set up should be able to talk to a smart tanks via APIs and work it out of its own for the most part. I realise the modulating down the power of an immersion heater required more electronics to match the export accurately, but if that is going to cost _£500 to be installed I might stick with my current approach.

Had mine working for a month or so now and initially set to a 100w export limit modified from the default 50w.

I've now had it set for 50w for a few days and the weather and load in the house has been up and down with lots of solar and a lot less and loads on and off and the unit has not that I've seen any way discharged the battery but has very nicely followed the excess whilst still keeping the battery as lead.

@anglefire one nice feature which I enabled recently is the timed boost option, I've set mine to boost for an hour during cheap rate. Only cuts in if there was not enough sun during the day or some hot water used in the eve. With a full house hold it means there is plenty of hot water and 0 need to use gas.

locked unfortunately I don’t get cheap electric as I don’t have an ev and the octopus tariff changed to requiring one to get on it. Otherwise I would do it in the morning as I have to heat the water in the morning as our solar is bias towards the later part of the day.

anglefire Octopus isn't the only TOU tariff supplier. We do have an EV and recently changed to EdF's EV tariff but I don't remember them needing proof of ownership. At the end of the day, the tariff's are about shifting your load to a time when demand is low. I'm not sure that requiring EV ownership is entirely fair if you've the ability to adapt your use to help smooth demand. My wife used to say that our house came alive at night when we had Economy 7. Not only did the storage heaters warm up, but the washing machine, tumble drier, dishwasher and immersion heater all came on.

I was speaking to a chap who works at a pumped storage power plant the other day, he said they used to pump at night and generate during the morning and teatime peaks. They still generate when the peaks occur but pump mostly during the day now, maybe reflecting that solar input both reduces demand and increases supply?

Tim Ahh so I'm not going mad, I've started to notice them pull several of their units in around lunch now at Dinorwig, presumably ready for the 5pm rush. Its quite fascinating to match the grid morph in quite a short space of time. Could do with a other one if that size and capacity though!

Tim

hoggy

I was fortunate enough to go to Dinorwig in about 1984 when I was a student and got to see a lot more than the normal tour (I know I've been since with the inlaws 😉 )
They generally pumped up the hill when there was excess and down when there was demand - and always had one generator spinning on standby to take up any big spikes - like the loss of a traditional generator.
Actually put my hand on the casing of the pump with it on standby - remarkably warm!
It takes something like 30seconds to go from pumping up the hill to generating - and from memory (All this is from memory!) only a second or so for the standby to be running full chat.

anglefire @hoggy Yep. That's the one. I've also visited a number of times but not since I retired from the industry a few years back (our factories didn't produce steam, just neutrons). They synchronise the units, spinning in air and "open the tap" if despatched by National Grid when the grid frequency drops. There's also Ffestiniog quite nearby, but that's only got 18MW units rather than the 300MW of Dinorwig.

Oh and I understand that dinorwig is one of only a couple of places that could restart the grid following a total failure.

I’ve also been in a nuclear reactor. As in inside. It was being built at the time. Fascinating place.

anglefire there used to be a fair few that can pull that trick but a lot of them have shut last few years. We did a test run on Drax years ago, start the entire plant essentially from a 12V car battery, in an ever increasing cascade of generators and gas turbines until you've got enough to get a coal unit in. Then the next one and so on from 0 - 4GW.
West Burton can do the same and ironically Little Barford, which was involved in the whole Hornsea network blackout a few years back!
Anyway I could talk about this stuff for years but I'll try not derail iboost thread any further!